Chuck



(N0 Model.)

J. HARTNESS.

CHUCK.

Patented Mar. 29 1898.

w Si UNITED STATES PATENT EEICE.

JAMES HARTNESS, or SPRINGFIELD, vEEMoNT.

SPECIFICATION forming part of Letters Patent N o. 601,513, dated March29, 1898.

' Application filed May 18, 1897.` Serial No. 637,044. (No model.)

To LZZ whom, t may concern:

Be it known that I, JAMES HAETNESs, of Springeld, in the county ofWindsor and State of Vermont, have invented certain new and usefulImprovements in Chucks, of which the following is a specification.

This invention, which relates to lathechucks, has for its object toprovide certain improvements in the construction of the chuck-jawslooking towarda more advantageous contact with the work which they hold.

The invention consists in the improved construction of chucks which Ishall now proceed to describe and claim.

Of the accompanying drawings, forming part of this specification, Figurel represents a face view of a three-j aw chuck constructed according tomy invention. Fig. 2 represents a section on the line 2 2 of Fig. l.Fig. 3 is a detail perspective view which will be further referred tohereinafter. Fig. 4 represents a face view of a modified construction.Fig. 5 represents an edge view of the same. Fig. 6 represents a sectionon line 6 6 of Fig. 4.

The same reference characters indicate the same parts in all thefigures.

Referring to the drawings, in which is represented a universal chuck ofthe scroll type, this being selected merely to illustrate an applicationor embodiment of my invention, the letters a, and b designate,respectively, the back plate and the face-plate, which together make upthe body of the chuck and are held together by screws c c, the backplateb being centrally bored and threaded ata' to receive the end of thelive-spindle of a lathe. cavity between the two plates is located thescroll-plate CZ, upon the face of which is formed the spiral thread orscroll d', which is employed to operate the jaws e e. To turn thescroll-plate, a bevel gear-pinion f is provided, which meshes withgear-teeth on the back of said plate and by its turning operates to movethe chuck-jaws in or out in their guides, the said jaws being providedwith threads on their rear portions, which engage the thread on thescroll-plate.

It is common at present to bring the chuckjaws directly into contactwith the work which is being held, the jaws being provided with suitablegripping portions or bites of various shapes adapted to the character ofthe work.

In the' With the ordinary three-jaw chuck having three points ofconta'ct'lthe work a thin ring, such as thev 'ringfw o similar piece ofwork, is apt to be bentout of shape more or less by the pressure of thejaws. In order to obviate this and other objections of a like characterarising from the old construction, I provide the inner end of each jaw ewith a pivoted V-shaped dog g, as shown, there being (where the chuck isa three-j awed one) an angle of one-hundred and twenty degrees betweenthe sides of the V in order to lobtain tangential contact withcylindrical Work. The dogs are pivoted on shouldered pins g2, whichscrew into the ends of the jaws, and each is rounded on its outer end tothe arc of a true circle concentric with the pivot, the

rounded portion fitti-ng against a comple# mental rounded shoulder e onthe jaw. These shoulders, which are shown clearly in Fig. 3, givebacking to the dogs and are made somewhat -shorter than the segmentalportions thereof in order to allow a small amount of rotation or pivotalplay to each dog. This pivotal ad justability is very important, sinceit allows the dogs to adapt themselves to irregularities in the surfaceof thework and distributes evenly the pressure of the jaws thereon. Itwill be seen that by this construction I have provided siX'points ofcontact with the ring w instead of three. These contact-points, with theabove-mentioned angle between the V-arms and up to certain diameterlimits depending upon the length of said arms, will be equally spacedaround a cylindrical body, such as the ring w, and the liability tobending of the same is greatly decreased.

As indicated in Figs. 4, 5, and 6, I have also embodied my invention inan attachment adapted for use on the ordinary forms of chuck-jawswithout the necessity of a special construction. As here shown, theattachment consists of a pivoted dog c, similar to those vjust describedand mounted on a block h,

which is recessed and provided with a setscrew h', by means of which itmay be clamped to the ordinary form of chuck-jaw. Said jaw then becomesthe equivalent of those shown in Figs. l, 2, and 3 and operates in asimilar manner to hold thework.

My improvements may be applied to uni- IOO . oted to oscillatetransversely to the axis of the chuck, and each provided with a V-shapedrecess, whereby the pressure of the jaws is distributed and equalizedupon the work.

3. An attachment for chuck-jaws comprising a recessed block adapted tobe clamped to the working portion of the jaw, and a dog pivoted theretoand adapted to oseillate in a plane transverse to the aXis of the chuck.

In testimony whereof 1 have signed my name to this speciiication, in thepresence of Vtwo subscribing witnesses, this 13th day of May, A. D.1897. y

JAMES I-IARTNESS.

Witnesses:

D. S. BROWNELL, J. W. BENNETT.

